Lifting jack



Aug. 21, 1934. p c pw cz 1,970,619

LIFTING JACK Filed Aug. 14 1935 Patented Aug. 21, 1934 LIFTINGJACK Edmund Pachowicz, Chicago, Ill.,iassignor to Templeton, Kenly & Co. Limited, Chicago, 111.,

a corporation of Illinois Application August '14, 1933, Serial No. 684,998 I f a claims. (c1, 254-.-9s)

This invention relates to improvements in lift,- ing jacks and it consists of the matters hereinafter described and more particularly pointed out in the appended claims. i

The jacks with which my invention is more particularly concerned are of the kind embodying therein a standard, in which is mcunted two telescoping screw members, which are adapted to-be successively projected out of and retracted into the standard.

One of the objects of the present invention is to provide a simple braking mechanism for the outer threaded member of the telescoping screws so as to hold said outer threaded member against rotation at certain times in the operation of the jack for its intended purpose. I

Another object of the invention is to provide a mechanism of this kind which is distorted from its original condition during its insertion into its intended position in the standard and is held in this distorted condition and against removal by the outer member of the screw with which it engages with the braking action desired.

The above mentioned objects of the invention as well as others, together with the many advantages thereof, will more fully appear as I proceed with my specification.

In the drawing:

Fig. 1 is a view in elevation of a double screw jack embodying the preferred form of the invention, with certain parts broken away to more clearly disclose the structure thereof;

Fig. 2 is a horizontal transverse section through the jack as taken on the line 2-2 of Fig. 1; and

Fig. 3 is a top plan view of the braking shoe or spring in its original condition and illustrates in dotted lines, the shape into which it is distorted when applied in position in the jack standard.

Referring now in detail to that embodiment of the invention, illustrated in the accompanying drawing:

1 indicates the tubular standard of the jack having a horizontally extended base 2 at its bottom end and upon which the jack stands upright. At the top end of the standard is preferably an integral yoke 3 enclosing a downwardly facing bevel gear 4, said gear having a hub at its top end. An antifriction thrust bearing 5 is disposed between the bottom of said gear and the top end of the tubular standard. The gear 4 is provided with internal threads and in effect forms the rotating nut of the jack.

To rotate the gear 4, a meshing pinion 6 is journalled in a laterally extending tubular boss '7 forming a part of the yoke 3, the pinion 6 being so constructedas to receive the usual handle (not shown) whereby it may be turned in the desired direction. 7

8 indicates theouter tubular screw of the jack. This screw is externally threaded for engagement 601 with the internal threads of the gear i andis internally threaded toreceive the inner screw 9. The external threads of the outer screw terminate short of the bottom end of the screw so that said screw cannot be projected entirely out of the gear 4 in the operation of the jack. The top end of the inner screw carries a swiveling cap 10.

To impose a braking action on the outer screw so as to hold it against turning with the gear 4 during the initial part of its rotation and thus cause projection of the outer screw, which carries the inner one therewith, I provide the following simple arrangement:

In the top end of the standard, in opposite sides thereof, in the plane of the yoke 3, are formed openings 11-11 that communicate with the interior of the standard. In connection therewith,

I provide a braking element 12 in the form of a bow shaped spring including an arched center portion 13 and oppositely extending straight end portions 14.14. This spring may be entered into the standard from one side thereof through one of the openings 11 until each end part extends through an associated opening. Said spring, of course, is inserted into place before the outer screw is assembled in place.

In assembling the screws 8 and 9 into the standard, this is done from the bottom end of the standard. During this assembly, the arched portion of the spring is distorted or deformed into substantially a semi-circular shape (as shown in dotted lines in Fig. 3) so that the top end of the outer screw may pass the same in the insertion of the screw from the bottom end of the standard. The distortion of the spring may be accomplished from the top end of the standard, before assembly of the gear 4, merely by reaching in from the top end of the standard with the finger or a suitable tool and pressing said arch portion toward one side of the interior of the standard.

With the spring thus distorted, the assembled screws are inserted in place from the bottom end of the standard, the spring being held distorted until the top end of the outer screw is passed beyond the same. With the screws in place, the spring will act as a spring pressed shoe having a good snug frictional engagement with the periphcry of the external threads of the outer screw.

When the jack is being operated in lifting a load, the spring so engages the periphery of the is just the rever se of that described; r

7 It is'p'ointed out that the spring'employed is wide enough to constantly engage at least two of the threads on the outer screw. Thus as the screw travels'past the spring, a surface engage ment providing that friction necessary to hold the be reachable in. removing the spring from the screw against free turning is obtained.

Should the spring become worn beyond usefulness, the outer screw is turned'so as to be withdrawn from the bottom of the gear 4 and when the screw has passed below thespri'ng; the worn spring is removed and replaced by a new one. Thereafter the screw and gear are replaced'and the jack is again ready for service. I v

.The improved braking deviceconsistsof but a single element that may be made at a relativelyv lowcost audit is easy to assemble into its intended positionin the jack. 1 r Y Whilein describing the invention, 1 have referred in detail to theform, arrangement and construction of the various parts of the jack, the

same is to be considered only, in an illustrative sense so that I do not Wishto be limited thereto except as-may be specifically set forthin the appended claims.

I claim as my invention:

1. In a jack of the kind described, the combination of a standard, a nut rotatably mounted on the top end of the standard, means for rotating said nut, a screw disposed in the bore of said standard and operatively engaged in the nut, a flat spring element having straight ends arranged in openings in substantially opposite sides of the standard and including a curved portion between said ends disposed in the bore of said standard and having a braking engagement with a peripheral portion of said screw at least one of said spring ends being so arranged in its opening as to standard. 2. In a jacket thekind described, the combination of a tubular standard, a nut rotatably mountedonthe top end or the standard, a screw disposed in the bore of said standard and operatively engaged in the nut, there being openings in wall portions of said tubular standard, a fiat spring element insertableinto the bore of said standard through one of said openings and having substan-. tially straight ends engaged in said openings after being so inserted andincluding a distorted curved portion between said ends disposed in said bore andfrictionally engaged with a portion of the screw.

. EDMUND PAC'HOWICZ 

